two of the points took awhile to fix and was off by .08’ - .09’ east horizontal.
I've considered this sort of thing for a while.
My dad was a PLS. In the normal course of working together, I would criticize his work, and ask for an explanation. His sometimes comeback was "Nathan, is was the best I could do under the circumstances".
He was a good dad.
Well, with GPS, the constellations are in continuous motion. There are better times of the day. And poorer times. (In the 1980's, it was only times, and not enough satellites time).
So, when a gnss unit gives you an answer, (especially during a poor time of the day), your GPS says: "it's the best I could do under the circumstances".
If you want the best performance from gnss, mission planning improves "the circumstances".
Nate
@on_point Darn Longitude, will we ever completely solve it?:) https://www.pbs.org/wgbh/nova/longitude/
@nate-the-surveyor in the early 90’s was doing a subdivision layout rough cl ad apprx lot locations on front corners so developer could walk the property and see where he wanted changes made. He had promised the lady who owned the property that certain trees and spots would be protected. Any way this other group of people came out protesting to stop killing the trees any of them. One lady literally chained herself to a tree. She was there a few days. For a young dumb rokkie i was like what is going on. They finally got her off the property. That little subdivision is still in last time i went home. I still remember dropping my hp 32s ii in a man hole doing as built and didn’t realize i had dropped it until a exam that night as i was taking a elementary surveying course. I still have that 32s ii it doesn’t work anymore but I somehow can never throw it away. It was my daily go to for my first 10 years. Fit in my shirt po with my cigarettes back then. So glad i gave up smoking though.
My dad was a PLS. In the normal course of working together, I would criticize his work, and ask for an explanation. His sometimes comeback was "Nathan, is was the best I could do under the circumstances".
He was a good dad.
That is a wonderful approach to life, applying that to ourselves and to others.
You know, dad was direct in his communication.
Of all the things I miss the most about dad, I miss his criticism.
He could look at a complex plat, and find real fault, in 2 or 3 minutes. It used to bother me. Now I miss it.
Nate
Lots of good discussion here - but here is my simple experience: I am using Carlson BRX7 (Hemisphere S631) with Carlson SurvPC 6.* (RT4 DC, will go to SurvPC 7) and getting fascinating results. It has lied (fibbed) to me a couple of times, but good practices have caught things with tolerances I find unacceptable so far. The fibs weren't that bad, maybe 0.12'H & 0.23'V is an example that sticks in mind.
Here are some common shots with a Javad.
Some of these are the same point. On the one up against the tree, I came back later, and shot it again. It was 0.16' off. I was shocked. Then, I looked carefully. The pipe had been bent, since my first shot.
The Algorithms in Javad's data collection is mighty fine.
Nate
This was my first real test of the capabilities of BRX7/SurvPC under canopy (Aug. 2022). Checked with the TS as I was skeptical. I don't remember the results other than I found them acceptable to use under my required Indiana class of survey (suburban 0.13' + 100ppm). I can't say enough that responsible technique, checking, and possibly adjustment of results are necessary if you want to use GPS this way. After a few months I didn't rely on checking with the gun (as much) and learned to review the raw file measurement info. I really like the LSA/GNSS Analysis function in SurvPC 6.* - haven't switched to 7 yet.
I can't say enough that responsible technique, checking, and possibly adjustment of results are necessary if you want to use GPS this way.
10000% agreement there.
What I like about Javad, is that it does if for you. And, if it is a super challenging place, I get it 2x or 3x. And, sometimes it does poorly during times of poor Sat. geometry. Or, lower sat count.
It gives you a visual warning, from the screen, that it's a poor shot.
Maybe I can post some pics later.
Kudos to Carlson, for getting in on it, BUT!
as Scott above said, You had BETTER be checking it. Right on.
N
So I had a project that involved planes trains and automobiles so i went to the field. This was boundary easements and airport runway. I am pooped. But we had some corners deep in canopy. As we were doing our recon I told the crew chief to bring along the rover. R10 base r12 rover. I had set some control via vrs rtk and then set the base up on it and established some more control in this few mile radius as we located prop corners and other items. As we where walking looking for evidence of possession because i had no deeds no plats yet. We had the cart before the horse. We found a old pipe next to a 8ft tall concrete block wall fence 3 ft north westerly that wall ran easterly and northerly as well as a chainlink fence tall with barbwire leaning out towards us that ran northerly and westerly. All in cedar oak pine thickness. The chainlink fence was .3 ft from pipe. Exactly due south 18 inch hickory tree .5 to edge. I said set up and let it set and i will walk this line and if it gets under a foot take a reading on it so when we do get deeds i have something to starf from. I walked and found some more pipes and irons about 500 and 1000 ft along that line. When i got back he said it got down under .10 vertical and .07 horizontal DRMS for those who care. We got. 120 epochs and moved on locating the rest of the random pipes we could find. About 3:45 pm the biss sends me a pdf of a plat and a link to 33 more pdfs containing the rest of the research. I set i. Truck and started the old inversing and getting my internal angles from plat bearings so i can see if we missed anything etc. As i did this i saw we were 34 seconds off the plat bearings on that thick line and distance was .08 ft. I said heck lets run this sucker out now. So we moved the base and hit a few of our control the 2nd time and found all the corners all checking as i comped them on the fly now that we had information other than just visual field evidence. Next morning as i was trying to get the old joints to work again i said lets go hit that ones in canopy first. We went the worst one with wall fence chainlink fence etc. different base location way different constellation. BAM 190 epochs less than .08 inverse. Hit the rest. Finished mapping all boundary corners hit twice all rtk vrs and base rover. All control. After adjustment least squares that point and everything on that site matched less than 13 seconds bearing and .08ft platted deeded measurements and my repeat measurements. A little patience and redundancy you can gnss in the canopy. I figured the first day it took 15 minutes for him to wait max. Long enough for me to walk and call the pipes up at about 500 and 1000 ft and walk back. Probably a lot quicker as we had been pushing it hard and crew chief was resting. The one that blew me away the most as that was a nasty spot. Boundary and control met the alta specs even though it was not required i just ran it for a easy way today to show the boss. He likes reading it versus the adjustment report. I am happy as the plat fits on all 1” pipes with ease lol.
@scott-bordenet I am amazed at what is achievable with full constellation myself. You are doing it correct just build checks. And understanding of requirements. Is that a 5600 robot. Those things are bullet proof but heavy toting on a traverse. I bet you will not miss hauling that heavy joker through the woods traversing anymore lol.
Yes, 5600's are bullet proof - except when your local Trimble service won't recalibrate and change internal batteries anymore. That 5601 will die eventually. That realization is what started my quest for new equipment. My hope was a GPS unit that worked in the woods like Javad. Started looking at Javad, but without the ability to add a TS to the equipment/DC, I ended up looking elsewhere and found Carlson. I just don't think I can operate w/o a TS on occasion, and I don't want to keep pushing points/survey files between equipment sets.
@scott-bordenet curious - is that running off a VRS network? I bought a BRX7 myself with SurvPC 6.XX back in september. I love it and I have always enjoyed Trimble products but just couldn't stomach the price difference out of pocket (tested a R12i and BRX7 against each other with awesome results from both to be honest)
@scott-bordenet Yes once the internal battery goes it becomes a paperweight. If you can back up the firmware in side then the internal battery is not to bad just ground yourself because static electricity could fry the board. But I think you are on the right track. I could see a good gnss set up and a plane old total station not even a robot for those few situations of rtk not working. Robot is good for solo if doing staking and such but boundary wise a bipod and a little extra walking even a one man band could get by with just a total station and gnss most of the time. I use to have contacts for the old repair folks that retired i bet some if them still can keep the 5601 running.
As shown in my videos, it is running off another BRX7 base. In Indiana, the INDOT VRS network (free) is only GPS/GLONASS for now. So I set a primary project CP from INDOT VRS to establish a SPC datum, then set the base on it and go base/rover. Using base rover setup, I can take advantage of GPS/GLONASS/BEIDOU/GALILEO. The four constellations with Surefix check is what I am trusting more and more (but check! and run averaging routine of your choice for multiple sessions.).
